Production of ingots and other metal castings



Patented July 28, 1925.

UNITED STATES PATENT 0mm.

PAUL RICHARD KUEHNBIOH, OF SHEFFIELD, ENGLAND.

PRODUCTION '01 INGOTS AND OTHER METAL GASTIITGS.

1T0 Drawing.

To all whom it may concern:

Be it known that I, PAUL RICHARD KonriNRIoH, a subject of the King of England, residing at Shefiield, in-"Yorkshire,

England, have invented certain new and useful Improvements in or Relating to the Production of Ingots and Other Metal Castings v(for which I filed an application for patent in Great Britain, Serial No. 3,769, on the 8th February, 1923) and I do hereby declare that the following is a full, clear, and exact description of the same.

This invention relates to the production of ingots and other metal castings, particucasting heat they are removed from the moulds to. soaking pits where they are" al- ,lowed to remain until their temperatures are equalized before being rolled, and in other cases it is sometimes the practice to place ingots in ashes to cool more or less slowly during the ensuing twelve or twentyfour hours. According; to the present invention, however, an ingot or other steel casting is stripped from its mould and placed in a suita le container under condi- .tions which ensure'very slow coolin It is an important and essential feature 0 the invention that the surface or skin of the ingot or casting shall still be at a higher temperature than the .recalescence point or critical hardenin temperature of the metalconcerned w en the conditions to ensure slow cooling are completed. Such conditions are conveniently and preferably provided by covering the ingot or casting with kieselguhr or other known suitable heat insulatmg powder. 1

t 1s preferred to strip the ingot or casting as soon as possible after a skin of sufficient. strength has formed to prevent bleeding, distortion or other damage. The latest period to which stripping may safely be delayed in order to carry out the invention is when the coolest part of the skin or surthe present invention, a less thic facture of Application filed January 28, 1924. SeriaI'No. 688,097.

face has 7 reached a temperature of from about 100 C. to 200 C. above the recalescence point, depending upon the time taken in stripping and placing the ingot or casting in the container and surrounding it with heat insulating material or conditions.

A further essential feature of the invention is that "therate of cooling of the ingot or casting shall be so slow that a period of at least about 96 hours is required for the metal to'cool to a temperature at which it is immune from any hardening effect due to an increase inthe rate of cooling and that the slow cooling conditions shall be maintained for that period. By such means both hardening of the .metal and the production of internal stresses are prevented.

As an example quite small ingots of .from

fifty to one hundred pounds in weight are slowly cooled through about four days and the conditions are such that they do not becomecold until about the end of this period. I

This is the preferred rate of cooling for. all

sizes of ingots or castings-in car mg out ess of heat insulating material being required for the larger ingots, as their natural rate of' cooling is slower.

Although the present invention may be applied in the manufacture of any steel ingot or casting which is desired in a. soft state, it is articularly useful in the manuum steels, rustless steel,"and other special steel alloys. High speed steel ingots or gh speed steels, nickel chromiingots of like nature subjected to a treatment according tothe invention are, when cold, in a state of virginal softness and ingots or castings when made from any of the various allo s so treated may be readily guch ingots or castings are also quite free from internal stresses,'and without removin any'part of the surface by machining, c ipping, or grinding, produce when forged, outinto bars material remarkably free from surface defects which are ususltlly very'prevalent in high class alloy stee s.

What I claim is The method of producing an ingot or other metal casting in a state of ,vlrginal softness by strippm it from the mould whilst its surface or .is still at a higher temperature than the recalescence Ipoint or critical hardening temperature of t emetal concerned, immediately lacing it in a con- In testimony whereof I hereunto aflix my tainer and surrounding 1t with heat insulatsignature. ing material of suflicient thickness to reduce the rate of cooling so that a period of at PAUL RICHARD KUEHNRICH' least about 96 hours is required for the in- Witnesses:

got or casting to become cold, substantially ARTHUR H'. GREENWOOD,

as specified. HAWTHORN WRIGHT. 

